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Chemical composition and crystal structure of mineral at Amphoe Chiang Khan, Loei Province, Thailand

Weerasak Somkhunthot*, Duengrudee Tessanan

The powder samples of mineral were prepared by the crush at room temperature and calcination at 600-900oC in air for 3 h. The chemical composition and crystal structure of as crushed and calcined powders were analyzed byX-ray fluorescence spectrometry (XRF) and X-ray diffractometer (XRD).XRF analysis indicated that the oxygen (O), silicon (Si), aluminium (Al), phosphorus (P), calcium (Ca), and sulfur (S) contents of a crushed powderwere about 52.160, 32.480, 7.886, 4.466, 1.936, and 1.070%, respectively. Similar analytical results were detected fromthe calcined powders. The compounds of a crushed powder included the silicon dioxide (SiO2, 69.490%), aluminium oxide (Al2O3, 14.900%), diphosphorus pentaoxide (P2O5, 10.230%), calciumoxide (CaO, 2.709%), and sulfur trioxide (SO3, 2.672%). The results showed small differences in the compositions of the calcined powders. These results showed that the mineral are SiO2-Al2O3- P2O5-CaO-SO3 compounds. XRD analysis found that the intensity of (1 7 2), (1 11 1), and (2 8 2) peaks of SiO2were relatively large compared to the other peaks. The small peaks observed the planes of CaO and SO3 while the Al2O3 and P2O5 are not detected. The XRD results show the traces of SiO2 phase in the powders, and the monoclinic lattice parameters are less than the reference. These preliminary studies can be used as an important platformfor further research.